Silicon elastomers, such as polydimethylsilicone or General Electric's room temperature vulcanizable (RTV) silicone elastomer compounds, have recently become very interesting materials for the construction of fluid flow systems. This is partly a result of the low modulus of elasticity, which enables the deformation of these materials with small applied pressures and very easy integration into small valves and pumps. Another advantage these materials bring with them is the easy processing of microstructures into them by replication molding or embossing. Finally, these materials are generally biocompatible and have been optimized to seal hermetically to most surfaces such as Si3N4 or SiO2.
Apart from replication molding, injection molding or embossing, there are presently few other methods for processing these technologically important materials. Indeed, the fluidic devices which are used for pumping, examining and sorting of small quantities of solutions are generally fabricated by either replication molding or embossing the elastomer material using a microfabricated die. Conventional photoresist processing is more difficult on elastomers since the large surface tension prevents the spin-coating of continuous films with uniform thickness. Chemical etching of these materials is also difficult, due to the very stable chemical structure. Organic solvents such as toluene are usually used to dissolve silicone elastomers, but such dissolution does not yield a directional pattern transfer.
What is needed is some type of methodology whereby elastomers may be microfabricated without the difficulties and limitations of prior art methods.